Pen sac and method of making same



Oct. 10,, 19 50 A. RHOTON 2,525,272

PEN SAC AND METHOD OF MAKING SAME Filed Feb. 5, 1.947

ilzoone Mylo/z Zazezc Coayalarzi la fez:

Patented Oct. 10, 1950 UNITED STATES PA] 2,525,272 7 PEN SAC AND METHOD OF MAKING SAWE Albert L. Rhoton, Akron, Ohio, assignor to The B. F. Goodrich Company, New York, N. 51., a corporation of New York.

Application February 5, 1947, Serial No. 726,497 g 7 Claims.

This invention relates to a method of making a laminated article such as a pen sac for use in a fountain pen or a similar article and is concerned more particularly with a pen sac having an outer cover comprising a vulcanized rubber lined with a layer of a superpolyamide.

The objects of this invention include providing a laminated article which is impervious to solvents such as hydrocarbons and fatty acids'or esters, and more particularly providing a pen sac which is impervious to ink and particularly to inks in which such solvents'are present; making a laminated article and particularly a pen sac of laminated construction by a method adapted to bond the laminations together; constructing a pen sac or other article by means of a minimum number of simple operations; and generall to provide a pen sac having the necessary requisites of stability, resiliency, strength,

and air impermeability in addition to ink resistance characteristics. Other objects will be apparent from the description which follows.

By means of this invention a seamless article such as a pen sac is constructed which comprises a lining layer of a superpolyamide providing ink and solvent resistance and a covering therefor of a vulcanized rubber. The covering preferably comprises a rubbery copolymer of butadiene and acrylonitrile and the covering layer is preferably obtained by deposition di- :1.

rectly from a latex of the copolymer upon a layer of the superpolyamide supported on a suitably shaped form. r

The preferred method of constructing a pen sac embodying this invention is best illustrated by reference to the drawings of which:

Fig. 1 is a schematic representation ofv the sequence of dipping operations in the preferred method of constructing a pen sac; and

Fig. 2 is a perspective view of a pen sac embodying this invention; the sac being sectioned for clarity of illustration.

The method of constructing a pen sac inaccordance with this invention comprises coating a suitably shaped form with a continuous layer of a superpolyamide, applying thereover a continuous covering of a vulcanizable rubber and thereafter vulcanizin the rubber. For the purposes of this invention the superpolyamide is preferably coated on the form by dipping the form in a solution of thesuperpolyamide in a suitable solvent and evaporating the solvent from the solution film adhering to the form.

The rubber is preferably applied over the superpolyamide layer by depositing a layer of coagulum on the coated form directly from a latex dispersion either by coating the form with a coagulant and immersing it in the latex bath or by spraying latex on a coagulant-coated form or by simultaneous spraying of latex and coagulant on the form.

I have discovered that superior adhesion is obtained between the rubber and the superpolyamide by applying a relatively thin coat of latex directly on the superpolyamide before the coagulant is applied and then depositing the main body of rubber thereon. The adhesion is especially marked where the rubber comprises a rubbery copolymer of butadiene and acrylonitrile. Adhesion sufficient for most purposes is obtained by applying the coagulant directly to the superpolyamide coating but it is preferred that the latex coating be applied first in order to overcome any tendency of the laminations to separate when the sac is flexed.

In the preferred method, a suitably shaped form I0 is provided as a deposition base for the article. This form may be of any suitable nonporous material but is preferably of porcelain, stainless steel, or aluminum. The form is coated with a material adapted to prevent adhesion of subsequent coatings to the form; that is, a ma' terial which coats the form and is nonadherent to both the form and the subsequent coating layers and which thus functions as a lubricant so that the pen sac may be stripped from the form with a minimum of effort and without injury to the sac. An aqueous dispersion of a polymeric silicone is preferably used as a lubricant or stripping aid, although any suitable material such as dispersions of talc, soapstone, soap solutions, mineral oil, etc., may be used. The form is dipped into the silicone dispersion, dried, and then into a superpolyamide solution as in Fig. l.

The superpolyamide preferably used is the ordinary commercial superpolyamide known to the trade as nylon although any of the filmforming superpolyamides including interpolyamides may be used, as exemplified by polymeric hexamethylene adipamide. The superpolyamide is preferably dissolved in methyl alcohol because of the low cost and availability of this solvent although any suitable volatile solvent'or solvent mixture may be used or an aqueous dispersion may be used. The formis removed from-the superpolyamide solution and the solvent evaporated from the solution film adhering to the form by blowing air onto the form, heating it, or merely allowing it to stand in the air. This process may be repeated giving a thicker continuous coating of superpolyamide on the form.

The superpolyamide coated form is dipped into a latex or aqueous dispersion of a rubbery copolymer of butadiene and acrylonitrile. This latex is preferably a copolymer of 55 parts of butadiene .and 45 parts of acrylonitrile containing a vulcanizing agent and accelerator therefor and suitable filler materials which are disclosed more fully in the preferred composition hereinafter set forth. Sufiice it to say that the commonly used filler materials for rubber such as carbon black, whiting, clay, titanium dioxide, etc., may be used and the accelerators may include any vulcanization accelerators for such a copolymer including such materials as 2-mercaptobenzothiazole, diphenyl guanidine, etc. Other rubbery copolymers of butadiene and acrylonitrile may also be used alternatively, such as the 65:33 copolymer or the 75:25 copolymer or similar copolymers which are flexible rubberlike materials. The latex coating need not be dried before proceeding further.

The coated form is next dipped in a bath of coagulant preferably comprising calcium nitrate dissolved in alcohol although any of the commonly used latex coagulants such as acids, other water soluble polyvalent metal salts etc., may be used. The coagulant film may be concentrated by evaporating part or all of the solvent therefrom if desired.

The coagulant coated form is again dipped into the latex dispersion for a time suflicient to deposit a layer of coagulum of the desired thickness on the form. By this method the coagulant salt layer is between layers of the copolymer rather than between the copolymer and the superpolyamide. This is desirable because the coagulant does not prevent adhesion between layers of the copolymer, I

The unvulcanized pen sac thus formed is washed in water to remove excess coagulant therefrom,- dried and vulcanized on the form in the usual manner. The vulcanized sac is then stripped from the form and in its finished condition exhibits flexibility, strength, air imperme- -l ability and resistance to ink. The nylon layer provides resistance to hydrocarbons, fatty acids and esters, and the copolymer layer furnishes additional resistance to any solvent which gets through the nylon lining as well as providing the f desired resiliency and flexibility of the finished pen sac. The component layers are strongly bonded together and do not separate when the sac is flexed.

Any vulcanizable rubber whether natural or synthetic may be used in practising this invention to give the pen sac the desired flexibility and strength. Thus for example, the rubber may comprise natural rubber from whatever source derived; synthetic rubber such as the rubbery a;

copolymers of butadiene with styrene, acrylonitrile, or similar copolymerizable monomers as well other laminated articles and particularly in making seamless articles.

For purposes of illustration, an example of preferred compositions used in practising this invention will be detailed, but the example is not intended to limit the scope of the invention.

Example An aluminum form is dipped in a 2% dispersion of silicone (DowCorning Mold Release Fluid Emulsion No. in water, dried, redipped and again dried. The lubricant coated form is immersed in a nylon solution having the composition:

Grams superpolyamide (nylon type 6A) Methyl alcohol 405 Water 45 I Total 500 The .form is warmedto evaporate the solvent, again dipped and dried to give a layer of nylon of about 0.002" total thickness.

The dried nylon coated form is dipped in a latex'dispersion having the recipe:

' Parts by weight Butadiene acrylonitrile' latex (:45 copolymer-42% T. S.) Ammonia 3.5 Fillers (clay, titanium dioxide and carbon black) 20.0?

Sulphur 1L5 Z-mercaptobenzothiazole 1.0

Total 126.0

The form is removed from the latex and, without drying the latex layer,.the coatedform is next dipped in a saturated solution of calcium nitrate in acetone, dried, again lowered into the latex dispersion and maintained in the dispersion until a coagulum 0.004 thick is deposited thereon. The unvulcanized sac obtained is washed in water for 30 minutes, dried in air for 3 hours at F. and then vulcanized by heating for 2 hours at 260 F.

The vulcanized pen sac prepared in this manner is flexible, impermeable to air and resistant to ink. The component layers are strongly bonded together and do not separate upon repeated flexing. The rubbery layer imparts body and resiliency to the article whereby the article returns to its original shape after deformation.

The example sets forth a preferred embodiment of the-invention, but it will be understood that the proportions of the constituents may be varied, other butadiene acrylonitrile copolymers may be used, any film-forming superpolyamide may be used, and the method of obtaining a laminated article embodying this invention may be varied or modified within the scope of the invention as defined in the appended claims.

..Iclaim: I

l. The method of' making a pen sac which comprises applying to a form of suitable shape a film of a solution of nylon in a volatile solvent, drying the nylon bearing film thereon, coating said nylon film with a latex of a vulcanizable rubber, applying a coagulant for said latex to said coating while said latex coating is still Wet and" thereafter associating the coagulant-bearing coating with a;-latex of a vulcanizable rubber to build up a deposit of latex coagulum thereon.

2. The method of making a pen sac which comprises-dipping a form therefor into a solution of superpolyamide in a volatile solvent, removing the form from the solution and evaporating the solvent from the film of superpolyamide solution adhering to the form, dipping the form into said superpolyamide solution, removing the form therefrom, again evaporating the solvent from said adherent film, dipping the coated form into a latex dispersion of a vulcanizable rubber, dipping the latex coated form into a coagulant for said latex while said latex coating is still wet, immersing the coagulant bearing form into said latex dispersion for a time sufficient to deposit a layer of coagulum thereon and thereafter vulcanizing the coagulum.

3. The method of making a pen sac which comprises coating a suitably shaped form with a lubricant adapted to prevent subsequent coating materials from adhering thereto, building up a continuous layer of nylon thereon by dipping the form in a solution of nylon in a volatile solvent and evaporating the solvent from the film adhering to said form, immersing the nylon coated portion of the form in a dispersion of a vulcanizable rubber latex containing a vulcanizing agent therefor, applying a coagulant for said latex to said coated form without drying the coated form, immersing said coated form in said latex to coagulate a layer of said latex thereon and thereafter vulcanizing the layer of coagulum.

4. The method of making a pen sac which comprises coating a suitably shaped form with a lubricant adapted to prevent coating materials from adhering thereto, building up a continuous layer of a superpolyamide on said form by alternately dipping said form in an alcohol solution of superpolyamide and evaporating the solvent from the adherent solution film, dipping the superpolyamide coated form in a copolyrnerized rubbery butadiene acrylonitrile latex containing a vulcanizing agent for the copolymer, thereafter dipping the latex coated form in a coagulant for said polymer without drying the latex coated form, subsequently depositing a layer of coagulum thereon by immersing the form in said' latex, washing the said coagulum and thereafter vulcanizing the deposited copolymer.

5. The method of making a pen sac which comprises coating a form therefor with a silicone, depositing a layer of nylon on said form, applying thereover a continuous coating of rubbery copolymeric butadiene acrylonitrile latex containing a vulcanizing agent for the copolymer, wetting said latex coating with a coagulant therefor while said latex coating is still wet, coagulating said latex on said form in a continuous layer and thereafter vulcanizing the deposited copolymer.

6. A pen sac comprising a layer of nylon having in direct adherent contact therewith a vulcanized layer of a rubbery butadiene acrylonitrile copolymer.

7. The method of adhering a latex coagulum to a superpolyamide surface which comprises applying directly to said surface an aqueous dispersion of a vulcanizable rubber, applying to said coated surface a coagulant for said dispersion, thereafter associating said coagulant-coated surface with an aqueous dispersion of a vulcanizable rubber to build up a deposit of coagulum upon said surface, and heating the resultant structure to vulcanize the vulcanizable portions thereof.

ALBERT L. RHOTON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Num er Name Date 1,959,556 Trobridge May '22, 1934 2,125,957 Sager Aug. 9, 1938 2,416,962 Stather-Dunn Mar. 4, 1947 2,421,613 Gray June 3, 1947 2,432,061 Chesler Dec. 2, 1947 

1. THE METHOD OF MAKING A PEN SAC WHICH COMPRISES APPLYING TO A FORM OF SUITABLE SHAPE A FILM OF A SOLUTION OF NYLON IN A VOLATILE SOLVENT, DRYING THE NYLON BEARING FILM THEREON, COATING SAID NYLON FILM WITH A LATEX OF A VULCANIZABLE RUBBER, APPLYING A COAGULANT OF SAID LATEX TO SAID COATING WHILE SAID LATEX COATING IS STILL WET AND THEREAFTER ASSOCIATING THE COAGULANT-BEARING COATING WITH A LATEX OF A VULCANIZABLE RUBBER TO BUILD UP A DEPOSIT OF LATEX COAGULUM THEREON. 